title: MR spectroscopy of liver in overweight children and adolescents: investigation of ¹H T₂ relaxation times at 3T.
abstract: OBJECTIVE
  The objective was to investigate T(2) relaxation values and to optimize hepatic fat quantification using proton MR spectroscopy ((1)H MRS) at 3T in overweight and obese children and adolescents.
  
  
  METHODS
  The study included 123 consecutive children and adolescents with a body mass index above the 97th percentile according to age and sex. (1)H MR spectroscopy was performed at 3.0 T using point resolved spectroscopy sequence with series TE. T(2) relaxation values and hepatic fat content corrected for the T(2) relaxation effects were calculated.
  
  
  RESULTS
  T(2) values for water ranged from 22 ms to 42 ms (mean value 28 ms) and T(2) values for fat ranged from 36 ms to 99 ms (mean value 64 ms). Poor correlation was observed: (1) between T(2) relaxation times of fat and T(2) relaxation times of water (correlation coefficient r=0.038, P=0.79); (2) between T(2) relaxation times of fat and fat content (r=0.057, P=0.69); (3) between T(2) relaxation times of water and fat content (r=0.160, P=0.26). Correlation between fat peak content and the T(2) corrected fat content decreased with increasing echo time TE: r=0.97 for TE=45, r=0.93 for TE=75, r=0.89 for TE=105, P<0.0001.
  
  
  CONCLUSIONS
  (1)H MRS at 3T is an effective technique for measuring hepatic fat content in overweight and obese children and adolescents. It is necessary to measure T(2) relaxation values and to correct the spectra for the T(2) relaxation effects in order to obtain an accurate estimate of the hepatic fat content.
authors.affiliation: Department of Diagnostic Radiology, Copenhagen University Hospital Herlev, DK-2730 Herlev, Denmark. elcha@heh.regionh.dk
authors.forename: Elizaveta
authors.initials: E
authors.lastname: Chabanova
authors.forename: Dorthe S
authors.initials: DS
authors.lastname: Bille
authors.forename: Ebbe
authors.initials: E
authors.lastname: Thisted
authors.forename: Jens-Christian
authors.initials: JC
authors.lastname: Holm
authors.forename: Henrik S
authors.initials: HS
authors.lastname: Thomsen
mesh_terms: D050154:Adiposity; D000293:Adolescent; D000465:Algorithms; D002648:Child; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods* / Q000706:statistics & numerical data*; D008297:Male; D050177:Overweight / Q000453:epidemiology* / Q000503:physiopathology*; D011522:Protons; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D011522:Protons